Index: vm_reserv.c
===================================================================
--- vm_reserv.c
+++ vm_reserv.c
@@ -1030,56 +1030,38 @@
 static void
 vm_reserv_break(vm_reserv_t rv)
 {
-	int begin_zeroes, hi, i, lo;
+	u_long changes;
+	int bitpos, hi, i, lo;
 
 	vm_reserv_assert_locked(rv);
 	CTR5(KTR_VM, "%s: rv %p object %p popcnt %d inpartpop %d",
 	    __FUNCTION__, rv, rv->object, rv->popcnt, rv->inpartpopq);
 	vm_reserv_remove(rv);
 	rv->pages->psind = 0;
-	i = hi = 0;
-	do {
-		/* Find the next 0 bit.  Any previous 0 bits are < "hi". */
-		lo = ffsl(~(((1UL << hi) - 1) | rv->popmap[i]));
-		if (lo == 0) {
-			/* Redundantly clears bits < "hi". */
+	hi = lo = 0;
+	for (i = 0; i <= NPOPMAP; i++) {
+		if (i == NPOPMAP)
+			changes = 1;
+		else {
+			changes = rv->popmap[i];
+			changes ^= (changes << 1) | (lo == hi);
 			rv->popmap[i] = 0;
-			rv->popcnt -= NBPOPMAP - hi;
-			while (++i < NPOPMAP) {
-				lo = ffsl(~rv->popmap[i]);
-				if (lo == 0) {
-					rv->popmap[i] = 0;
-					rv->popcnt -= NBPOPMAP;
-				} else
-					break;
+		}
+		while (changes != 0) {
+			bitpos = ffsl(changes) - 1;
+			changes ^= 1UL << bitpos;
+			if (lo == hi)
+				lo = NBPOPMAP * i + bitpos;
+			else {
+				hi = NBPOPMAP * i + bitpos;
+				vm_domain_free_lock(VM_DOMAIN(rv->domain));
+				vm_phys_free_contig(&rv->pages[lo], hi - lo);
+				vm_domain_free_unlock(VM_DOMAIN(rv->domain));
+				lo = hi;
 			}
-			if (i == NPOPMAP)
-				break;
-			hi = 0;
 		}
-		KASSERT(lo > 0, ("vm_reserv_break: lo is %d", lo));
-		/* Convert from ffsl() to ordinary bit numbering. */
-		lo--;
-		if (lo > 0) {
-			/* Redundantly clears bits < "hi". */
-			rv->popmap[i] &= ~((1UL << lo) - 1);
-			rv->popcnt -= lo - hi;
-		}
-		begin_zeroes = NBPOPMAP * i + lo;
-		/* Find the next 1 bit. */
-		do
-			hi = ffsl(rv->popmap[i]);
-		while (hi == 0 && ++i < NPOPMAP);
-		if (i != NPOPMAP)
-			/* Convert from ffsl() to ordinary bit numbering. */
-			hi--;
-		vm_domain_free_lock(VM_DOMAIN(rv->domain));
-		vm_phys_free_contig(&rv->pages[begin_zeroes], NBPOPMAP * i +
-		    hi - begin_zeroes);
-		vm_domain_free_unlock(VM_DOMAIN(rv->domain));
-	} while (i < NPOPMAP);
-	KASSERT(rv->popcnt == 0,
-	    ("vm_reserv_break: reserv %p's popcnt is corrupted", rv));
+	}
+	rv->popcnt = 0;
 	counter_u64_add(vm_reserv_broken, 1);
 }
 
@@ -1289,7 +1271,8 @@
 {
 	vm_paddr_t pa, size;
 	vm_reserv_t rv, rvn;
-	int hi, i, lo, low_index, next_free;
+	u_long changes;
+	int bitpos, hi, i, lo, low_index;
 
 	if (npages > VM_LEVEL_0_NPAGES - 1)
 		return (FALSE);
@@ -1323,26 +1306,40 @@
 			/* Start the search for free pages at "low". */
 			low_index = (low + PAGE_MASK - pa) >> PAGE_SHIFT;
 			i = low_index / NBPOPMAP;
-			hi = low_index % NBPOPMAP;
-		} else
-			i = hi = 0;
+			bitpos = low_index % NBPOPMAP;
+			changes = rv->popmap[i] | ((1UL << bitpos) - 1);
+		} else {
+			i = 0;
+			changes = rv->popmap[i];
+		}
+		lo = hi = 0;
+		changes ^= (changes << 1) | 1;
 		do {
-			/* Find the next free page. */
-			lo = ffsl(~(((1UL << hi) - 1) | rv->popmap[i]));
-			while (lo == 0 && ++i < NPOPMAP)
-				lo = ffsl(~rv->popmap[i]);
-			if (i == NPOPMAP)
-				break;
-			/* Convert from ffsl() to ordinary bit numbering. */
-			lo--;
-			next_free = NBPOPMAP * i + lo;
-			pa = VM_PAGE_TO_PHYS(&rv->pages[next_free]);
+			if (lo >= hi) {
+				while (changes == 0 && ++i < NPOPMAP) {
+					changes = rv->popmap[i];
+					changes ^= (changes << 1) | (lo == hi);
+				}
+				if (i == NPOPMAP)
+					bitpos = 0;
+				else {
+					bitpos = ffsl(changes) - 1;
+					changes ^= 1UL << bitpos;
+				}
+				if (lo == hi) {
+					lo = NBPOPMAP * i + bitpos;
+					continue;
+				}
+				hi = NBPOPMAP * i + bitpos;
+			}
+			pa = VM_PAGE_TO_PHYS(&rv->pages[lo]);
 			KASSERT(pa >= low,
 			    ("vm_reserv_reclaim_contig: pa is too low"));
 			if (pa + size > high) {
 				/* The rest of this reservation is too high. */
 				break;
-			} else if ((pa & (alignment - 1)) != 0 ||
+			}
+			if ((pa & (alignment - 1)) != 0 ||
 			    ((pa ^ (pa + size - 1)) & ~(boundary - 1)) != 0) {
 				/*
 				 * The current page doesn't meet the alignment
@@ -1351,33 +1348,16 @@
 				 * of its free pages are either excluded or
 				 * exhausted.
 				 */
-				hi = lo + 1;
-				if (hi >= NBPOPMAP) {
-					hi = 0;
-					i++;
-				}
+				++lo;
 				continue;
 			}
-			/* Find the next used page. */
-			hi = ffsl(rv->popmap[i] & ~((1UL << lo) - 1));
-			while (hi == 0 && ++i < NPOPMAP) {
-				if ((NBPOPMAP * i - next_free) * PAGE_SIZE >=
-				    size) {
-					vm_reserv_reclaim(rv);
-					vm_reserv_unlock(rv);
-					return (TRUE);
-				}
-				hi = ffsl(rv->popmap[i]);
+			if ((hi - lo) * PAGE_SIZE < size) {
+				lo = hi;
+				continue;
 			}
-			/* Convert from ffsl() to ordinary bit numbering. */
-			if (i != NPOPMAP)
-				hi--;
-			if ((NBPOPMAP * i + hi - next_free) * PAGE_SIZE >=
-			    size) {
-				vm_reserv_reclaim(rv);
-				vm_reserv_unlock(rv);
-				return (TRUE);
-			}
+			vm_reserv_reclaim(rv);
+			vm_reserv_unlock(rv);
+			return (TRUE);
 		} while (i < NPOPMAP);
 		vm_reserv_unlock(rv);
 		vm_reserv_domain_lock(domain);